Helsinki is the capital of Finland, and the currency used in Finland is the euro. Finland introduced the euro on January 1, 2002, to replace the Finnish markka.
Finland is the only Scandinavian country to adopt the euro. Denmark has opted out. Sweden has yet to change critical laws to accept it, and Norway has not yet joined the European Union.
The current USD exchange rate is shown on the Bank of Finland's website.
You can exchange money in banks in Finland or in currency exchanges. Many people just use ATMs, which are located all over the country and are indicated by an OTTO sign. Most major credit cards are accepted at ATMs, and if you use a non-Finnish credit card, the instructions will appear in English. Do not confuse a Maksut machine for an ATM--these are more complicated and are used for such tasks as paying bills.
Most major credit cards are widely accepted in Finland, including American Express, Diners Club, Visa and MasterCard.
Traveler's checks can be cashed by banks, exchange offices and most major hotels. Smaller shops, particularly outside Helsinki, may not accept them.